Öztürk, EmrahEmrahÖztürkKaspar, KevinKevinKasparFaulwasser, TimmTimmFaulwasserWorthmann, KarlKarlWorthmannKepplinger, PeterPeterKepplingerRheinberger, KlausKlausRheinberger2025-11-192025-11-192025-10-27Sustainable Energy, Grids and Networks 44: 102033 (2025)https://hdl.handle.net/11420/58820The increasing penetration of volatile renewables and growing electricity demand pose several challenges for power systems. Simultaneously, flexible devices – so called distributed energy resources (DER) – are becoming more widespread, making them attractive for providing ancillary services. The flexibility of a single device can be represented by a set of reference power profiles, and the flexibility of multiple devices by the summation of individual flexibility sets. However, set addition, also known as the Minkowski sum, is usually computationally intractable. This has led to the development of various approximation methods in the literature. The current study improves upon our previously published vertex-based inner approximation, by extending it to more general storage devices and hierarchical aggregation settings. We validate the efficacy and accuracy of the proposed method through case studies using real data and provide the source code of the algorithm as a Python package that enables the (dis-)aggregation of various flexible devices in real-world scenarios.en2352-46772025Elsevier BVhttps://creativecommons.org/licenses/by/4.0/Flexibility aggregationDisaggregationDistributed energy resourcesEnergy storage systemsPythonMinkowski sum computationTechnology::621: Applied Physics::621.3: Electrical Engineering, Electronic EngineeringSocial Sciences::333: Economics of Land and EnergyComputer Science, Information and General Works::004: Computer SciencesJournal Articlehttps://doi.org/10.15480/882.1616310.1016/j.segan.2025.10203310.15480/882.16163Journal Article